Dynamically enabled vehicle-to-everything (v2x) pedestrian mode for mobile devices

ABSTRACT

A method of wireless communication by a device includes detecting whether the device is in an outdoor environment in response to a start of a reevaluation timer. The method also determines a mobility level of the device in response to the start of the reevaluation timer. The method further includes enabling a vehicle-to-everything (V2X) pedestrian mode in response to the device being in the outdoor environment and/or the mobility level exceeding a threshold value.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communications, andmore specifically to dynamically enabling and disabling avehicle-to-everything (V2X) pedestrian mode for mobile devices.

BACKGROUND

Wireless communications systems are widely deployed to provide varioustelecommunications services such as telephony, video, data, messaging,and broadcasts. Typical wireless communications systems may employmultiple-access technologies capable of supporting communications withmultiple users by sharing available system resources. Examples of suchmultiple-access technologies include code division multiple access(CDMA) systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, orthogonal frequency divisionmultiple access (OFDMA) systems, single-carrier frequency divisionmultiple access (SC-FDMA) systems, and time division synchronous codedivision multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in varioustelecommunications standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. An example telecommunications standardis fifth generation (5G) new radio (NR). 5G NR is part of a continuousmobile broadband evolution promulgated by Third Generation PartnershipProject (3GPP) to meet new requirements associated with latency,reliability, security, scalability (e.g., with Internet of Things(IoT)), and other requirements. 5G NR includes services associated withenhanced mobile broadband (eMBB), massive machine type communications(mMTC), and ultra-reliable low latency communications (URLLC). Someaspects of 5G NR may be based on the fourth generation (4G) long termevolution (LTE) standard. There exists a need for further improvementsin 5G NR technology. These improvements may also be applicable to othermulti-access technologies and the telecommunications standards thatemploy these technologies.

Wireless communications systems may include or provide support forvarious types of communications systems, such as vehicle relatedcellular communications systems (e.g., cellular vehicle-to-everything(CV2X) communications systems). Vehicle related communications systemsmay be used by vehicles to increase safety and to help preventcollisions of vehicles. Information regarding inclement weather, nearbyaccidents, road conditions, and/or other information may be conveyed toa driver via the vehicle related communications system. In some cases,sidelink user equipment (UEs), such as vehicles, may communicatedirectly with each other using device-to-device (D2D) communicationsover a D2D wireless link. These communications can be referred to assidelink communications.

As the demands for sidelink communications increase in general, and CV2Xtechnology specifically penetrates the market and the number of carssupporting CV2X communication grows rapidly, the CV2X network isexpected to become increasingly crowded, especially for peak trafficscenarios. As a result, the chance of colliding allocations between UEsmay increase. An allocation collision may prevent successful decoding ofat least one of the colliding UE transmissions and in some cases mayprevent all of the colliding UE transmissions from being decoded. Forsafety reasons, there is a need to minimize the duration of repetitivecollisions between semi-persistently scheduled allocations of collidinguser equipments (UEs) or to minimize the number of future collisions ingeneral.

SUMMARY

In aspects of the present disclosure, a method of wireless communicationby a device includes detecting whether the device is in an outdoorenvironment in response to a start of a reevaluation timer. The methodalso includes determining a mobility level of the device in response tothe start of the reevaluation timer. The method further includesenabling a vehicle-to-everything (V2X) pedestrian mode in response tothe device being in the outdoor environment and/or the mobility levelexceeding a threshold value.

Other aspects of the present disclosure are directed to an apparatus forwireless communication by a device having a memory and one or moreprocessors coupled to the memory. The processor(s) is configured todetect whether the device is in an outdoor environment in response to astart of a reevaluation timer. The processor(s) is also configured todetermine a mobility level of the device in response to the start of thereevaluation timer. The processor(s) is further configured to enable avehicle-to-everything (V2X) pedestrian mode in response to the devicebeing in the outdoor environment and/or the mobility level exceeding athreshold value.

Other aspects of the present disclosure are directed to an apparatus forwireless communication by a device including means for detecting whetherthe device is in an outdoor environment in response to a start of areevaluation timer. The apparatus also includes means for determining amobility level of the device in response to the start of thereevaluation timer. The apparatus further includes means for enabling avehicle-to-everything (V2X) pedestrian mode in response to the devicebeing in the outdoor environment and/or the mobility level exceeding athreshold value.

Aspects generally include a method, apparatus, system, computer programproduct, non-transitory computer-readable medium, user equipment, basestation, wireless communications device, and processing system assubstantially described with reference to and as illustrated by theaccompanying drawings and specification.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described. The conception and specificexamples disclosed may be readily utilized as a basis for modifying ordesigning other structures for carrying out the same purposes of thepresent disclosure. Such equivalent constructions do not depart from thescope of the appended claims. Characteristics of the concepts disclosed,both their organization and method of operation, together withassociated advantages will be better understood from the followingdescription when considered in connection with the accompanying figures.Each of the figures is provided for the purposes of illustration anddescription, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the above-recited features of the present disclosure can beunderstood in detail, a more particular description, briefly summarizedabove, may be had by reference to aspects, some of which are illustratedin the appended drawings. It is to be noted, however, that the appendeddrawings illustrate only certain typical aspects of this disclosure andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects. The samereference numbers in different drawings may identify the same or similarelements.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network.

FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a firstfifth generation (5G) new radio (NR) frame, downlink (DL) channelswithin a 5G NR subframe, a second 5G NR frame, and uplink (UL) channelswithin a 5G NR subframe, respectively.

FIG. 3 is a diagram illustrating an example of a base station and userequipment (UE) in an access network.

FIG. 4 is a diagram illustrating an example of a vehicle-to-everything(V2X) system, in accordance with various aspects of the presentdisclosure.

FIG. 5 is a block diagram illustrating an example of avehicle-to-everything (V2X) system with a road side unit (RSU),according to aspects of the present disclosure.

FIG. 6 is a graph illustrating a sidelink (SL) communications scheme, inaccordance with various aspects of the present disclosure.

FIG. 7 is a flow diagram illustrating a decision process for determiningwhether to enable a pedestrian mode, in accordance with various aspectsof the present disclosure.

FIG. 8 is a flow diagram illustrating a decision process for determiningwhether a device is outdoors and near vehicular traffic, in accordancewith various aspects of the present disclosure.

FIG. 9 is a flow diagram illustrating a decision process for setting areevaluation timer, in accordance with various aspects of the presentdisclosure.

FIG. 10 is a flow diagram illustrating an example process performed, forexample, by a device, in accordance with various aspects of the presentdisclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully below withreference to the accompanying drawings. This disclosure may, however, beembodied in many different forms and should not be construed as limitedto any specific structure or function presented throughout thisdisclosure. Rather, these aspects are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of thedisclosure to those skilled in the art. Based on the teachings, oneskilled in the art should appreciate that the scope of the disclosure isintended to cover any aspect of the disclosure disclosed, whetherimplemented independently of or combined with any other aspect of thedisclosure. For example, an apparatus may be implemented or a method maybe practiced using any number of the aspects set forth. In addition, thescope of the disclosure is intended to cover such an apparatus ormethod, which is practiced using other structure, functionality, orstructure and functionality in addition to or other than the variousaspects of the disclosure set forth. It should be understood that anyaspect of the disclosure disclosed may be embodied by one or moreelements of a claim.

Several aspects of telecommunications systems will now be presented withreference to various apparatuses and techniques. These apparatuses andtechniques will be described in the following detailed description andillustrated in the accompanying drawings by various blocks, modules,components, circuits, steps, processes, algorithms, and/or the like(collectively referred to as “elements”). These elements may beimplemented using hardware, software, or combinations thereof. Whethersuch elements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

It should be noted that while aspects may be described using terminologycommonly associated with 5G and later wireless technologies, aspects ofthe present disclosure can be applied in other generation-basedcommunications systems, such as and including 3G and/or 4G technologies.

In cellular communications networks, wireless devices may generallycommunicate with each other via one or more network entities such as abase station or scheduling entity. Some networks may supportdevice-to-device (D2D) communications that enable discovery of, andcommunications with nearby devices using a direct link between devices(e.g., without passing through a base station, relay, or another node).D2D communications can enable mesh networks and device-to-network relayfunctionality. Some examples of D2D technology include Bluetoothpairing, Wi-Fi Direct, Miracast, and LTE-D. D2D communications may alsobe referred to as point-to-point (P2P) or sidelink communications.

D2D communications may be implemented using licensed or unlicensedbands. Additionally, D2D communications can avoid the overhead involvingthe routing to and from the base station. Therefore, D2D communicationscan improve throughput, reduce latency, and/or increase energyefficiency.

A type of D2D communications may include vehicle-to-everything (V2X)communications. V2X communications may assist autonomous vehicles incommunicating with each other. For example, autonomous vehicles mayinclude multiple sensors (e.g., light detection and ranging (LiDAR),radar, cameras, etc.). In most cases, the autonomous vehicle's sensorsare line of sight sensors. In contrast, V2X communications may allowautonomous vehicles to communicate with each other for non-line of sightsituations.

Sidelink (SL) communications refers to the communications among userequipment (UE) without tunneling through a base station (BS) and/or acore network. Sidelink communications can be communicated over aphysical sidelink control channel (PSCCH) and a physical sidelink sharedchannel (PSSCH). The PSCCH and PSSCH are similar to a physical downlinkcontrol channel (PDCCH) and a physical downlink shared channel (PDSCH)in downlink (DL) communications between a base station and a UE. Forinstance, the PSCCH may carry sidelink control information (SCI) and thePSSCH may carry sidelink data (e.g., user data). Each PSCCH isassociated with a corresponding PSSCH, where SCI in a PSCCH may carryreservation and/or scheduling information for sidelink data transmissionin the associated PSSCH. Use cases for sidelink communications mayinclude, among others, vehicle-to-everything (V2X), industrial IoT(IIoT), and/or NR-lite.

Cellular vehicle-to-everything (V2X) technology has applications forimproving commuter safety. However, conventional cellular V2X technologydoes not adequately address safety issues relating to pedestrians.Nowadays, almost every person on the street has a mobile device, such asa mobile handset or cellular enabled wearable. Under that assumption,density of V2X coverage may be increased to improve safety.

Unfortunately, always running a V2X stack, such as a pedestrian mode, onmobile devices unjustifiably increases battery consumption of thosedevices. That is, running the V2X stack (e.g., enabling a pedestrianmode) operates more baseband and radio frequency (RF) components. Itwould be desirable to reduce the envelope of regular cellular operationwhen the user is likely not near vehicles. On the other hand, it wouldbe highly inconvenient and unrealistic to expect mobile users tomanually turn on and off the V2X stack on their devices according totheir environment or other relevant circumstances. Furthermore, mobiledevices always transmitting V2X signals may unnecessarily strain the V2Xspectrum. Power consumption may be reduced by allowing a device tooperate in transmit-only mode, without receiving any communications.

According to aspects of the present disclosure, a framework fordynamically enabling or disabling a pedestrian mode detects when and forhow long it would be beneficial to enable the pedestrian mode. Thesolution determines when it would be beneficial to enable the pedestrianmode, by detecting when the mobile user begins walking or running. Themotion detection may occur with assistance from a motion co-processor, alocation engine, and/or similar information verified by a pairedBluetooth wearable. Alternatively, the solution may detect a mobile userswitching from an indoor location to outdoor location, for example, bysensing a background noise level. The information may be reconfirmedwith an online look-up of the device's location on a map. For example,the look-up may indicate that the device is near a road, indicating thedevice is outside. The background noise may indicate the device movedfrom a calm environment, to a busy environment, and then to an activeenvironment. Other indications that the pedestrian mode should beenabled include the device having no wireless local area network (WLAN)connection or the device being within coverage of a number of globalnavigation satellite system (GNSS) devices (e.g., global positioningsystem (GPS) satellites). The pedestrian mode may also be enabled, forexample, when the device is detected to be outdoors, but not in a car,which may have its own dedicated V2X stack.

In other aspects of the present disclosure, an audio system of a userequipment (UE) operating in an always-ON state may detect an emergency.The emergency may be detected by sounds that identify distress, such asa car crash or explosion. In these aspects, the mobile user may chooseto contribute to a road safety mesh system that may rely on servicelayer information to propagate via multiple “hops” over V2X users. Inother words, the user may choose to participate in an ad-hoc meshnetwork.

Some aspects of the present disclosure determine when to disable thepedestrian mode. For example, the pedestrian mode may be disabled whendetermining a re-evaluation timer expired and no enable criteria is met.The pedestrian mode may be disabled when the device is determined to beindoors or far from vehicles. The pedestrian mode may be disabled whenit is determined that the user is driving in a car that is alreadyequipped with dedicated V2X system.

Techniques of the present disclosure improve a trade-off among havingvery dense V2X coverage for commuter safety, stationary mobile devicesunjustifiably draining battery power without much benefit, andunder-utilizing the unique interplay of complex systems that mobiledevices commonly support. Benefits to a maximum possible number ofmobile devices and vehicles with V2X transceivers may be provided. Thetechniques of the present disclosure may leverage devices that havecellular V2X (CV2X) support in addition to regular cellulartechnologies.

FIG. 1 is a diagram illustrating an example of a wireless communicationssystem and an access network 100. The wireless communications system(also referred to as a wireless wide area network (WWAN)) includes basestations 102, UEs 104, an evolved packet core (EPC) 160, and anothercore network 190 (e.g., a 5G core (5GC)). The base stations 102 mayinclude macrocells (high power cellular base station) and/or small cells102′ (low power cellular base station). The macrocells include basestations. The small cells 102′ include femtocells, picocells, andmicrocells.

The base stations 102 configured for 4G LTE (collectively referred to asevolved universal mobile telecommunications system (UMTS) terrestrialradio access network (E-UTRAN)) may interface with the EPC 160 throughbackhaul links 132 (e.g., S1 interface). The base stations 102configured for 5G NR (collectively referred to as next generation RAN(NG-RAN)) may interface with core network 190 through backhaul links184. In addition to other functions, the base stations 102 may performone or more of the following functions: transfer of user data, radiochannel ciphering and deciphering, integrity protection, headercompression, mobility control functions (e.g., handover, dualconnectivity), inter-cell interference coordination, connection setupand release, load balancing, distribution for non-access stratum (NAS)messages, NAS node selection, synchronization, radio access network(RAN) sharing, multimedia broadcast multicast service (MBMS), subscriberand equipment trace, RAN information management (RIM), paging,positioning, and delivery of warning messages. The base stations 102 maycommunicate directly or indirectly (e.g., through the EPC 160 or corenetwork 190) with each other over backhaul links 134 (e.g., X2interface). The backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Eachof the base stations 102 may provide communications coverage for arespective geographic coverage area 110. There may be overlappinggeographic coverage areas 110. For example, the small cell 102′ may havea coverage area 110′ that overlaps the coverage area 110 of one or moremacro base stations 102. A network that includes both small cell andmacrocells may be known as a heterogeneous network. A heterogeneousnetwork may also include home evolved Node Bs (eNBs) (HeNBs), which mayprovide service to a restricted group known as a closed subscriber group(CSG). The communications links 120 between the base stations 102 andthe UEs 104 may include uplink (UL) (also referred to as reverse link)transmissions from a UE 104 to a base station 102 and/or downlink (DL)(also referred to as forward link) transmissions from a base station 102to a UE 104. The communications links 120 may use multiple-input andmultiple-output (MIMO) antenna technology, including spatialmultiplexing, beamforming, and/or transmit diversity. The communicationslinks may be through one or more carriers. The base stations 102/UEs 104may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc., MHz)bandwidth per carrier allocated in a carrier aggregation of up to atotal of Yx MHz (x component carriers) used for transmission in eachdirection. The carriers may or may not be adjacent to each other.Allocation of carriers may be asymmetric with respect to DL and UL(e.g., more or fewer carriers may be allocated for DL than for UL). Thecomponent carriers may include a primary component carrier and one ormore secondary component carriers. A primary component carrier may bereferred to as a primary cell (PCell) and a secondary component carriermay be referred to as a secondary cell (SCell).

Certain UEs 104 may communicate with each other using device-to-device(D2D) communications link 158. The D2D communications link 158 may usethe DL/UL WWAN spectrum. The D2D communications link 158 may use one ormore sidelink channels, such as a physical sidelink broadcast channel(PSBCH), a physical sidelink discovery channel (PSDCH), a physicalsidelink shared channel (PSSCH), and a physical sidelink control channel(PSCCH). D2D communications may be through a variety of wireless D2Dcommunications systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee,Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi accesspoint (AP) 150 in communication with Wi-Fi stations (STAs) 152 viacommunications links 154 in a 5 GHz unlicensed frequency spectrum. Whencommunicating in an unlicensed frequency spectrum, the STAs 152/AP 150may perform a clear channel assessment (CCA) prior to communicating inorder to determine whether the channel is available.

The small cell 102′ may operate in a licensed and/or an unlicensedfrequency spectrum. When operating in an unlicensed frequency spectrum,the small cell 102′ may employ NR and use the same 5 GHz unlicensedfrequency spectrum as used by the Wi-Fi AP 150. The small cell 102′,employing NR in an unlicensed frequency spectrum, may boost coverage toand/or increase capacity of the access network.

A base station 102, whether a small cell 102′ or a large cell (e.g.,macro base station), may include an eNB, gNodeB (gNB), or another typeof base station. Some base stations, such as gNB 180 may operate in atraditional sub 6 GHz spectrum, in millimeter wave (mmWave) frequencies,and/or near mmWave frequencies in communication with the UE 104. Whenthe gNB 180 operates in mmWave or near mmWave frequencies, the gNB 180may be referred to as an mmWave base station. Extremely high frequency(EHF) is part of the radio frequency (RF) in the electromagneticspectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between1 millimeter and 10 millimeters. Radio waves in the band may be referredto as a millimeter wave. Near mmWave may extend down to a frequency of 3GHz with a wavelength of 100 millimeters. The super high frequency (SHF)band extends between 3 GHz and 30 GHz, also referred to as centimeterwave. Communications using the mmWave/near mmWave radio frequency band(e.g., 3 GHz-300 GHz) has extremely high path loss and a short range.The mmWave base station 180 may utilize beamforming 182 with the UE 104to compensate for the extremely high path loss and short range.

The base station 180 may transmit a beamformed signal to the UE 104 inone or more transmit directions 182′. The UE 104 may receive thebeamformed signal from the base station 180 in one or more receivedirections 182″. The UE 104 may also transmit a beamformed signal to thebase station 180 in one or more transmit directions. The base station180 may receive the beamformed signal from the UE 104 in one or morereceive directions. The base station 180/UE 104 may perform beamtraining to determine the best receive and transmit directions for eachof the base station 180/UE 104. The transmit and receive directions forthe base station 180 may or may not be the same. The transmit andreceive directions for the UE 104 may or may not be the same.

The EPC 160 may include a mobility management entity (MME) 162, otherMMEs 164, a serving gateway 166, a multimedia broadcast multicastservice (MBMS) gateway 168, a broadcast multicast service center (BM-SC)170, and a packet data network (PDN) gateway 172. The MME 162 may be incommunication with a home subscriber server (HSS) 174. The MME 162 isthe control node that processes the signaling between the UEs 104 andthe EPC 160. Generally, the MME 162 provides bearer and connectionmanagement. All user Internet protocol (IP) packets are transferredthrough the serving gateway 166, which itself is connected to the PDNgateway 172. The PDN gateway 172 provides UE IP address allocation aswell as other functions. The PDN gateway 172 and the BM-SC 170 areconnected to the IP services 176. The IP services 176 may include theInternet, an intranet, an IP multimedia subsystem (IMS), a PS streamingservice, and/or other IP services. The BM-SC 170 may provide functionsfor MBMS user service provisioning and delivery. The BM-SC 170 may serveas an entry point for content provider MBMS transmission, may be used toauthorize and initiate MBMS bearer services within a public land mobilenetwork (PLMN), and may be used to schedule MBMS transmissions. The MBMSgateway 168 may be used to distribute MBMS traffic to the base stations102 belonging to a multicast broadcast single frequency network (MBSFN)area broadcasting a particular service, and may be responsible forsession management (start/stop) and for collecting enhanced MBMS (eMBMS)related charging information.

The core network 190 may include an access and mobility managementfunction (AMF) 192, other AMFs 193, a session management function (SMF)194, and a user plane function (UPF) 195. The AMF 192 may be incommunication with a unified data management (UDM) 196. The AMF 192 isthe control node that processes the signaling between the UEs 104 andthe core network 190. Generally, the AMF 192 provides quality of service(QoS) flow and session management. All user Internet protocol (IP)packets are transferred through the UPF 195. The UPF 195 provides UE IPaddress allocation as well as other functions. The UPF 195 is connectedto the IP services 197. The IP services 197 may include the Internet, anintranet, an IP multimedia subsystem (IMS), a PS streaming service,and/or other IP services.

The base station 102 may also be referred to as a gNB, Node B, evolvedNode B (eNB), an access point, a base transceiver station, a radio basestation, a radio transceiver, a transceiver function, a basic serviceset (BSS), an extended service set (ESS), a transmit and receive point(TRP), or some other suitable terminology. The base station 102 providesan access point to the EPC 160 or core network 190 for a UE 104.Examples of UEs 104 include a cellular phone, a smart phone, a sessioninitiation protocol (SIP) phone, a laptop, a personal digital assistant(PDA), a satellite radio, a global positioning system, a multimediadevice, a video device, a digital audio player (e.g., MP3 player), acamera, a game console, a tablet, a smart device, a wearable device, avehicle, an electric meter, a gas pump, a large or small kitchenappliance, a healthcare device, an implant, a sensor/actuator, adisplay, or any other similar functioning device. Some of the UEs 104may be referred to as IoT devices (e.g., a parking meter, gas pump,toaster, vehicles, heart monitor, etc.). The UE 104 may also be referredto as a station, a mobile station, a subscriber station, a mobile unit,a subscriber unit, a wireless unit, a remote unit, a mobile device, awireless device, a wireless communications device, a remote device, amobile subscriber station, an access terminal, a mobile terminal, awireless terminal, a remote terminal, a handset, a user agent, a mobileclient, a client, or some other suitable terminology.

Referring again to FIG. 1 , in certain aspects, a device, such as the UE104, may include a pedestrian mode component 199 configured to detectwhether the device is in an outdoor environment in response to a startof a reevaluation timer. The pedestrian mode component 199 may also beconfigured to determine a mobility level of the device in response tothe start of the reevaluation timer. The pedestrian mode component 199may be configured to enable a vehicle-to-everything (V2X) pedestrianmode in response to the device being detected to be in the outdoorenvironment and/or the mobility level exceeding a threshold value.

Although the following description may be focused on cellular V2Xcommunications with respect to 5G NR, it may be applicable to othersimilar areas, such as LTE, LTE-A, CDMA, GSM, and other wirelesstechnologies.

FIG. 2A is a diagram 200 illustrating an example of a first subframewithin a 5G NR frame structure. FIG. 2B is a diagram 230 illustrating anexample of DL channels within a 5G NR subframe. FIG. 2C is a diagram 250illustrating an example of a second subframe within a 5G NR framestructure. FIG. 2D is a diagram 280 illustrating an example of ULchannels within a 5G NR subframe. The 5G NR frame structure may befrequency division duplex (FDD) in which for a particular set ofsubcarriers (carrier system bandwidth), subframes within the set ofsubcarriers are dedicated for either DL or UL, or may be time divisionduplex (TDD) in which for a particular set of subcarriers (carriersystem bandwidth), subframes within the set of subcarriers are dedicatedfor both DL and UL. In the examples provided by FIGS. 2A, 2C, the 5G NRframe structure is assumed to be TDD, with subframe 4 being configuredwith slot format 28 (with mostly DL), where D is DL, U is UL, and X isflexible for use between DL/UL, and subframe 3 being configured withslot format 34 (with mostly UL). While subframes 3, 4 are shown withslot formats 34, 28, respectively, any particular subframe may beconfigured with any of the various available slot formats 0-61. Slotformats 0, 1 are all DL, UL, respectively. Other slot formats 2-61include a mix of DL, UL, and flexible symbols. UEs are configured withthe slot format (dynamically through DL control information (DCI), orsemi-statically/statically through radio resource control (RRC)signaling) through a received slot format indicator (SFI). Note that thedescription infra applies also to a 5G NR frame structure that is TDD.

Other wireless communications technologies may have a different framestructure and/or different channels. A frame (10 ms) may be divided into10 equally sized subframes (1 ms). Each subframe may include one or moretime slots. Subframes may also include mini-slots, which may include 7,4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on theslot configuration. For slot configuration 0, each slot may include 14symbols, and for slot configuration 1, each slot may include 7 symbols.The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. Thesymbols on UL may be CP-OFDM symbols (for high throughput scenarios) ordiscrete Fourier transform (DFT) spread OFDM (DFT-S-OFDM) symbols (alsoreferred to as single carrier frequency-division multiple access(SC-FDMA) symbols) (for power limited scenarios; limited to a singlestream transmission). The number of slots within a subframe is based onthe slot configuration and the numerology. For slot configuration 0,different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots,respectively, per subframe. For slot configuration 1, differentnumerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, persubframe. Accordingly, for slot configuration 0 and numerology μ, thereare 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing andsymbol length/duration are a function of the numerology. The subcarrierspacing may be equal to 2{circumflex over ( )}μ*15 kHz, where μ is thenumerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacingof 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz.The symbol length/duration is inversely related to the subcarrierspacing. FIGS. 2A-2D provide an example of slot configuration 0 with 14symbols per slot and numerology μ=0 with 1 slot per subframe. Thesubcarrier spacing is 15 kHz and symbol duration is approximately 66.7μs.

A resource grid may represent the frame structure. Each time slotincludes a resource block (RB) (also referred to as physical RBs (PRBs))that extends 12 consecutive subcarriers. The resource grid is dividedinto multiple resource elements (REs). The number of bits carried byeach RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot)signals (RS) for the UE. The RS may include demodulation RS (DM-RS)(indicated as Rx for one particular configuration, where 100× is theport number, but other DM-RS configurations are possible) and channelstate information reference signals (CSI-RS) for channel estimation atthe UE. The RS may also include beam measurement RS (BRS), beamrefinement RS (BRRS), and phase tracking RS (PT-RS).

FIG. 2B illustrates an example of various DL channels within a subframeof a frame. The physical downlink control channel (PDCCH) carries DCIwithin one or more control channel elements (CCEs), each CCE includingnine RE groups (REGs), each REG including four consecutive REs in anOFDM symbol. A primary synchronization signal (PSS) may be within symbol2 of particular subframes of a frame. The PSS is used by a UE 104 todetermine subframe/symbol timing and a physical layer identity. Asecondary synchronization signal (SSS) may be within symbol 4 ofparticular subframes of a frame. The SSS is used by a UE to determine aphysical layer cell identity group number and radio frame timing. Basedon the physical layer identity and the physical layer cell identitygroup number, the UE can determine a physical cell identifier (PCI).Based on the PCI, the UE can determine the locations of theaforementioned DM-RS. The physical broadcast channel (PBCH), whichcarries a master information block (MIB), may be logically grouped withthe PSS and SSS to form a synchronization signal (SS)/PBCH block. TheMIB provides a number of RBs in the system bandwidth and a system framenumber (SFN). The physical downlink shared channel (PDSCH) carries userdata, broadcast system information not transmitted through the PBCH suchas system information blocks (SIBs), and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as Rfor one particular configuration, but other DM-RS configurations arepossible) for channel estimation at the base station. The UE maytransmit DM-RS for the physical uplink control channel (PUCCH) and DM-RSfor the physical uplink shared channel (PUSCH). The PUSCH DM-RS may betransmitted in the first one or two symbols of the PUSCH. The PUCCHDM-RS may be transmitted in different configurations depending onwhether short or long PUCCHs are transmitted and depending on theparticular PUCCH format used. Although not shown, the UE may transmitsounding reference signals (SRS). The SRS may be used by a base stationfor channel quality estimation to enable frequency-dependent schedulingon the UL.

FIG. 2D illustrates an example of various UL channels within a subframeof a frame. The PUCCH may be located as indicated in one configuration.The PUCCH carries uplink control information (UCI), such as schedulingrequests, a channel quality indicator (CQI), a precoding matrixindicator (PMI), a rank indicator (RI), and hybrid automatic repeatrequest (HARQ) acknowledgment/negative acknowledgment (ACK/NACK)feedback. The PUSCH carries data, and may additionally be used to carrya buffer status report (BSR), a power headroom report (PHR), and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with aUE 350 in an access network. In the DL, IP packets from the EPC 160 maybe provided to a controller/processor 375. The controller/processor 375implements layer 3 and layer 2 functionality. Layer 3 includes a radioresource control (RRC) layer, and layer 2 includes a service dataadaptation protocol (SDAP) layer, a packet data convergence protocol(PDCP) layer, a radio link control (RLC) layer, and a medium accesscontrol (MAC) layer. The controller/processor 375 provides RRC layerfunctionality associated with broadcasting of system information (e.g.,MIB, SIBs), RRC connection control (e.g., RRC connection paging, RRCconnection establishment, RRC connection modification, and RRCconnection release), inter radio access technology (RAT) mobility, andmeasurement configuration for UE measurement reporting; PDCP layerfunctionality associated with header compression/decompression, security(ciphering, deciphering, integrity protection, integrity verification),and handover support functions; RLC layer functionality associated withthe transfer of upper layer packet data units (PDUs), error correctionthrough automatic repeat request (ARQ), concatenation, segmentation, andreassembly of RLC service data units (SDUs), re-segmentation of RLC dataPDUs, and reordering of RLC data PDUs; and MAC layer functionalityassociated with mapping between logical channels and transport channels,multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing ofMAC SDUs from TBs, scheduling information reporting, error correctionthrough HARQ, priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370implement layer 1 functionality associated with various signalprocessing functions. Layer 1, which includes a physical (PHY) layer,may include error detection on the transport channels, forward errorcorrection (FEC) coding/decoding of the transport channels,interleaving, rate matching, mapping onto physical channels,modulation/demodulation of physical channels, and MIMO antennaprocessing. The TX processor 316 handles mapping to signalconstellations based on various modulation schemes (e.g., binaryphase-shift keying (BPSK), quadrature phase-shift keying (QPSK),M-phase-shift keying (M-PSK), M-quadrature amplitude modulation(M-QAM)). The coded and modulated symbols may then be split intoparallel streams. Each stream may then be mapped to an OFDM subcarrier,multiplexed with a reference signal (e.g., pilot) in the time and/orfrequency domain, and then combined together using an inverse fastFourier transform (IFFT) to produce a physical channel carrying a timedomain OFDM symbol stream. The OFDM stream is spatially precoded toproduce multiple spatial streams. Channel estimates from a channelestimator 374 may be used to determine the coding and modulation scheme,as well as for spatial processing. The channel estimate may be derivedfrom a reference signal and/or channel condition feedback transmitted bythe UE 350. Each spatial stream may then be provided to a differentantenna 320 via a separate transmitter 318TX. Each transmitter 318TX maymodulate an RF carrier with a respective spatial stream fortransmission.

At the UE 350, each receiver 354RX receives a signal through itsrespective antenna 352. Each receiver 354RX recovers informationmodulated onto an RF carrier and provides the information to the receive(RX) processor 356. The TX processor 368 and the RX processor 356implement layer 1 functionality associated with various signalprocessing functions. The RX processor 356 may perform spatialprocessing on the information to recover any spatial streams destinedfor the UE 350. If multiple spatial streams are destined for the UE 350,they may be combined by the RX processor 356 into a single OFDM symbolstream. The RX processor 356 then converts the OFDM symbol stream fromthe time-domain to the frequency domain using a fast Fourier transform(FFT). The frequency domain signal comprises a separate OFDM symbolstream for each subcarrier of the OFDM signal. The symbols on eachsubcarrier, and the reference signal, are recovered and demodulated bydetermining the most likely signal constellation points transmitted bythe base station 310. These soft decisions may be based on channelestimates computed by the channel estimator 358. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the base station 310 on the physicalchannel. The data and control signals are then provided to thecontroller/processor 359, which implements layer 3 and layer 2functionality.

The controller/processor 359 can be associated with a memory 360 thatstores program codes and data. The memory 360 may be referred to as acomputer-readable medium. In the UL, the controller/processor 359provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, and control signalprocessing to recover IP packets from the EPC 160. Thecontroller/processor 359 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DLtransmission by the base station 310, the controller/processor 359provides RRC layer functionality associated with system information(e.g., MIB, SIBs) acquisition, RRC connections, and measurementreporting; PDCP layer functionality associated with headercompression/decompression, and security (ciphering, deciphering,integrity protection, integrity verification); RLC layer functionalityassociated with the transfer of upper layer PDUs, error correctionthrough ARQ, concatenation, segmentation, and reassembly of RLC SDUs,re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; andMAC layer functionality associated with mapping between logical channelsand transport channels, multiplexing of MAC SDUs onto TBs,demultiplexing of MAC SDUs from TBs, scheduling information reporting,error correction through HARQ, priority handling, and logical channelprioritization.

Channel estimates derived by a channel estimator 358 from a referencesignal or feedback transmitted by the base station 310 may be used bythe TX processor 368 to select the appropriate coding and modulationschemes, and to facilitate spatial processing. The spatial streamsgenerated by the TX processor 368 may be provided to different antenna352 via separate transmitters 354TX. Each transmitter 354TX may modulatean RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a mannersimilar to that described in connection with the receiver function atthe UE 350. Each receiver 318RX receives a signal through its respectiveantenna 320. Each receiver 318RX recovers information modulated onto anRF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 thatstores program codes and data. The memory 376 may be referred to as acomputer-readable medium. In the UL, the controller/processor 375provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover IP packets from the UE 350. IP packets from thecontroller/processor 375 may be provided to the EPC 160. Thecontroller/processor 375 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and thecontroller/processor 359 may be configured to perform aspects inconnection with the pedestrian mode component 199 of FIG. 1 . In someaspects, the UE 104, 350 may include means for detecting, means fordetermining, means for enabling, means for adjusting, means forscanning, and/or means for disabling. Such means may include one or morecomponents of the UE 104, 350 described in connection with FIGS. 1 and 3.

FIG. 4 is a diagram of a device-to-device (D2D) communications system400, including V2X communications, in accordance with various aspects ofthe present disclosure. For example, the D2D communications system 400may include V2X communications, (e.g., a first UE 450 communicating witha second UE 451). In some aspects, the first UE 450 and/or the second UE451 may be configured to communicate in a licensed radio frequencyspectrum and/or a shared radio frequency spectrum. The shared radiofrequency spectrum may be unlicensed, and therefore multiple differenttechnologies may use the shared radio frequency spectrum forcommunications, including new radio (NR), LTE, LTE-Advanced, licensedassisted access (LAA), dedicated short range communications (DSRC),MuLTEFire, 4G, and the like. The foregoing list of technologies is to beregarded as illustrative, and is not meant to be exhaustive.

The D2D communications system 400 may use NR radio access technology. Ofcourse, other radio access technologies, such as LTE radio accesstechnology, may be used. In D2D communications (e.g., V2X communicationsor vehicle-to-vehicle (V2V) communications), the UEs 450, 451 may be onnetworks of different mobile network operators (MNOs). Each of thenetworks may operate in its own radio frequency spectrum. For example,the air interface to a first UE 450 (e.g., Uu interface) may be on oneor more frequency bands different from the air interface of the secondUE 451. The first UE 450 and the second UE 451 may communicate via asidelink component carrier, for example, via the PC5 interface. In someexamples, the MNOs may schedule sidelink communications between or amongthe UEs 450, 451 in licensed radio frequency spectrum and/or a sharedradio frequency spectrum (e.g., 5 GHz radio spectrum bands).

The shared radio frequency spectrum may be unlicensed, and thereforedifferent technologies may use the shared radio frequency spectrum forcommunications. In some aspects, a D2D communications (e.g., sidelinkcommunications) between or among UEs 450, 451 is not scheduled by MNOs.The D2D communications system 400 may further include a third UE 452.

The third UE 452 may operate on the first network 410 (e.g., of thefirst MNO) or another network, for example. The third UE 452 may be inD2D communications with the first UE 450 and/or second UE 451. The firstbase station 420 (e.g., gNB) may communicate with the third UE 452 via adownlink (DL) carrier 432 and/or an uplink (UL) carrier 442. The DLcommunications may use various DL resources (e.g., the DL subframes(FIG. 2A) and/or the DL channels (FIG. 2B)). The UL communications maybe performed via the UL carrier 442 using various UL resources (e.g.,the UL subframes (FIG. 2C) and the UL channels (FIG. 2D)).

The first network 410 operates in a first frequency spectrum andincludes the first base station 420 (e.g., gNB) communicating at leastwith the first UE 450, for example, as described in FIGS. 1-3 . Thefirst base station 420 (e.g., gNB) may communicate with the first UE 450via a DL carrier 430 and/or an UL carrier 440. The DL communications maybe use various DL resources (e.g., the DL subframes (FIG. 2A) and/or theDL channels (FIG. 2B)). The UL communications may be performed via theUL carrier 440 using various UL resources (e.g., the UL subframes (FIG.2C) and the UL channels (FIG. 2D)).

In some aspects, the second UE 451 may be on a different network fromthe first UE 450. In some aspects, the second UE 451 may be on a secondnetwork 411 (e.g., of the second MNO). The second network 411 mayoperate in a second frequency spectrum (e.g., a second frequencyspectrum different from the first frequency spectrum) and may includethe second base station 421 (e.g., gNB) communicating with the second UE451, for example, as described in FIGS. 1-3 .

The second base station 421 may communicate with the second UE 451 via aDL carrier 431 and an UL carrier 441. The DL communications areperformed via the DL carrier 431 using various DL resources (e.g., theDL subframes (FIG. 2A) and/or the DL channels (FIG. 2B)). The ULcommunications are performed via the UL carrier 441 using various ULresources (e.g., the UL subframes (FIG. 2C) and/or the UL channels (FIG.2D)).

In conventional systems, the first base station 420 and/or the secondbase station 421 assign resources to the UEs for device-to-device (D2D)communications (e.g., V2X communications and/or V2V communications). Forexample, the resources may be a pool of UL resources, both orthogonal(e.g., one or more frequency division multiplexing (FDM) channels) andnon-orthogonal (e.g., code division multiplexing (CDM)/resource spreadmultiple access (RSMA) in each channel). The first base station 420and/or the second base station 421 may configure the resources via thePDCCH (e.g., faster approach) or RRC (e.g., slower approach).

In some systems, each UE 450, 451 autonomously selects resources for D2Dcommunications. For example, each UE 450, 451 may sense and analyzechannel occupation during the sensing window. The UEs 450, 451 may usethe sensing information to select resources from the sensing window. Asdiscussed, one UE 451 may assist another UE 450 in performing resourceselection. The UE 451 providing assistance may be referred to as thereceiver UE or partner UE, which may potentially notify the transmitterUE 450. The transmitter UE 450 may transmit information to the receivingUE 451 via sidelink communications.

The D2D communications (e.g., V2X communications and/or V2Vcommunications) may be carried out via one or more sidelink carriers470, 480. The one or more sidelink carriers 470, 480 may include one ormore channels, such as a physical sidelink broadcast channel (PSBCH), aphysical sidelink discovery channel (PSDCH), a physical sidelink sharedchannel (PSSCH), and a physical sidelink control channel (PSCCH), forexample.

In some examples, the sidelink carriers 470, 480 may operate using thePC5 interface. The first UE 450 may transmit to one or more (e.g.,multiple) devices, including to the second UE 451 via the first sidelinkcarrier 470. The second UE 451 may transmit to one or more (e.g.,multiple) devices, including to the first UE 450 via the second sidelinkcarrier 480.

In some aspects, the UL carrier 440 and the first sidelink carrier 470may be aggregated to increase bandwidth. In some aspects, the firstsidelink carrier 470 and/or the second sidelink carrier 480 may sharethe first frequency spectrum (with the first network 410) and/or sharethe second frequency spectrum (with the second network 411). In someaspects, the sidelink carriers 470, 480 may operate in anunlicensed/shared radio frequency spectrum.

In some aspects, sidelink communications on a sidelink carrier may occurbetween the first UE 450 and the second UE 451. In some aspects, thefirst UE 450 may perform sidelink communications with one or more (e.g.,multiple) devices, including the second UE 451 via the first sidelinkcarrier 470. For example, the first UE 450 may transmit a broadcasttransmission via the first sidelink carrier 470 to the multiple devices(e.g., the second and third UEs 451, 452). The second UE 451 (e.g.,among other UEs) may receive such broadcast transmission. Additionallyor alternatively, the first UE 450 may transmit a multicast transmissionvia the first sidelink carrier 470 to the multiple devices (e.g., thesecond and third UEs 451, 452). The second UE 451 and/or the third UE452 (e.g., among other UEs) may receive such multicast transmission. Themulticast transmissions may be connectionless or connection-oriented. Amulticast transmission may also be referred to as a groupcasttransmission.

Furthermore, the first UE 450 may transmit a unicast transmission viathe first sidelink carrier 470 to a device, such as the second UE 451.The second UE 451 (e.g., among other UEs) may receive such unicasttransmission. Additionally or alternatively, the second UE 451 mayperform sidelink communications with one or more (e.g., multiple)devices, including the first UE 450 via the second sidelink carrier 480.For example, the second UE 451 may transmit a broadcast transmission viathe second sidelink carrier 480 to the multiple devices. The first UE450 (e.g., among other UEs) may receive such broadcast transmission.

In another example, the second UE 451 may transmit a multicasttransmission via the second sidelink carrier 480 to the multiple devices(e.g., the first and third UEs 450, 452). The first UE 450 and/or thethird UE 452 (e.g., among other UEs) may receive such multicasttransmission. Further, the second UE 451 may transmit a unicasttransmission via the second sidelink carrier 480 to a device, such asthe first UE 450. The first UE 450 (e.g., among other UEs) may receivesuch unicast transmission. The third UE 452 may communicate in a similarmanner.

In some aspects, for example, such sidelink communications on a sidelinkcarrier between the first UE 450 and the second UE 451 may occur withouthaving MNOs allocating resources (e.g., one or more portions of aresource block (RB), slot, frequency band, and/or channel associatedwith a sidelink carrier 470, 480) for such communications and/or withoutscheduling such communications. Sidelink communications may includetraffic communications (e.g., data communications, controlcommunications, paging communications and/or system informationcommunications). Further, sidelink communications may include sidelinkfeedback communications associated with traffic communications (e.g., atransmission of feedback information for previously-received trafficcommunications). Sidelink communications may employ at least onesidelink communications structure having at least one feedback symbol.The feedback symbol of the sidelink communications structure may allotfor any sidelink feedback information that may be communicated in thedevice-to-device (D2D) communications system 400 between devices (e.g.,a first UE 450, a second UE 451, and/or a third UE 452). As discussed, aUE may be a vehicle (e.g., UE 450, 451), a mobile device (e.g., 452), oranother type of device. In some cases, a UE may be a special UE, such asa road side unit (RSU).

FIG. 5 illustrates an example of a vehicle-to-everything (V2X) systemwith a roadside unit (RSU), according to aspects of the presentdisclosure. As shown in FIG. 5 , V2X system 500 includes a transmitterUE 504 transmits data to an RSU 510 and a receiving UE 502 via sidelinktransmissions 512. Additionally, or alternatively, the RSU 510 maytransmit data to the transmitter UE 504 via a sidelink transmission 512.The RSU 510 may forward data received from the transmitter UE 504 to acellular network (e.g., gNB) 508 via an UL transmission 514. The gNB 508may transmit the data received from the RSU 510 to other UEs 506 via aDL transmission 516. The RSU 510 may be incorporated with trafficinfrastructure (e.g., traffic light, light pole, etc.) For example, asshown in FIG. 5 , the RSU 510 is a traffic signal positioned at a sideof a road 520. Additionally or alternatively, RSUs 510 may bestand-alone units.

FIG. 6 is a graph illustrating a sidelink (SL) communications scheme, inaccordance with various aspects of the present disclosure. A scheme 600may be employed by UEs such as the UEs 104 in a network such as thenetwork 100. In FIG. 6 , the x-axis represents time and the y-axisrepresents frequency. The CV2X channels may be for 3GPP Release 16 andbeyond.

In the scheme 600, a shared radio frequency band 601 is partitioned intomultiple subchannels or frequency subbands 602 (shown as 602 _(S0), 602_(S1), 602 _(S2)) in frequency and multiple sidelink frames 604 (shownas 604 a, 604 b, 604 c, 604 d) in time for sidelink communications. Thefrequency band 601 may be at any suitable frequencies. The frequencyband 601 may have any suitable bandwidth (BW) and may be partitionedinto any suitable number of frequency subbands 602. The number offrequency subbands 602 can be dependent on the sidelink communicationsBW requirement.

Each sidelink frame 604 includes a sidelink resource 606 in eachfrequency subband 602. A legend 605 indicates the types of sidelinkchannels within a sidelink resource 606. In some instances, a frequencygap or guard band may be specified between adjacent frequency subbands602, for example, to mitigate adjacent band interference. The sidelinkresource 606 may have a substantially similar structure as an NRsidelink resource. For instance, the sidelink resource 606 may include anumber of subcarriers or RBs in frequency and a number of symbols intime. In some instances, the sidelink resource 606 may have a durationbetween about one millisecond (ms) to about 20 ms. Each sidelinkresource 606 may include a PSCCH 610 and a PSSCH 620. The PSCCH 610 andthe PSSCH 620 can be multiplexed in time and/or frequency. The PSCCH 610may be for part one of a control channel (CCH), with the second partarriving as a part of the shared channel allocation. In the example ofFIG. 6 , for each sidelink resource 606, the PSCCH 610 is located duringthe beginning symbol(s) of the sidelink resource 606 and occupies aportion of a corresponding frequency subband 602, and the PSSCH 620occupies the remaining time-frequency resources in the sidelink resource606. In some instances, a sidelink resource 606 may also include aphysical sidelink feedback channel (PSFCH), for example, located duringthe ending symbol(s) of the sidelink resource 606. In general, a PSCCH610, a PSSCH 620, and/or a PSFCH may be multiplexed within a sidelinkresource 606.

The PSCCH 610 may carry SCI 660 and/or sidelink data. The sidelink datacan be of various forms and types depending on the sidelink application.For instance, when the sidelink application is a V2X application, thesidelink data may carry V2X data (e.g., vehicle location information,traveling speed and/or direction, vehicle sensing measurements, etc.).Alternatively, when the sidelink application is an IIoT application, thesidelink data may carry IIoT data (e.g., sensor measurements, devicemeasurements, temperature readings, etc.). The PSFCH can be used forcarrying feedback information, for example, HARQ ACK/NACK for sidelinkdata received in an earlier sidelink resource 606.

In an NR sidelink frame structure, the sidelink frames 604 in a resourcepool 608 may be contiguous in time. A sidelink UE (e.g., the UEs 104)may include, in SCI 660, a reservation for a sidelink resource 606 in alater sidelink frame 604. Thus, another sidelink UE (e.g., a UE in thesame new radio unlicensed (NR-U) sidelink system) may perform SCIsensing in the resource pool 608 to determine whether a sidelinkresource 606 is available or occupied. For instance, if the sidelink UEdetected SCI indicating a reservation for a sidelink resource 606, thesidelink UE may refrain from transmitting in the reserved sidelinkresource 606. If the sidelink UE determines that there is no reservationdetected for a sidelink resource 606, the sidelink UE may transmit inthe sidelink resource 606. As such, SCI sensing can assist a UE inidentifying a target frequency subband 602 to reserve for sidelinkcommunications and to avoid intra-system collision with another sidelinkUE in the NR sidelink system. In some aspects, the UE may be configuredwith a sensing window for SCI sensing or monitoring to reduceintra-system collision.

In some aspects, the sidelink UE may be configured with a frequencyhopping pattern. In this regard, the sidelink UE may hop from onefrequency subband 602 in one sidelink frame 604 to another frequencysubband 602 in another sidelink frame 604. In the illustrated example ofFIG. 6 , during the sidelink frame 604 a, the sidelink UE transmits SCI660 in the sidelink resource 606 located in the frequency subband 602_(s2) to reserve a sidelink resource 606 in a next sidelink frame 604 blocated at the frequency subband 602 _(S1). Similarly, during thesidelink frame 604 b, the sidelink UE transmits SCI 662 in the sidelinkresource 606 located in the frequency subband 602 _(S1) to reserve asidelink resource 606 in a next sidelink frame 604 c located at thefrequency subband 602 _(S1). During the sidelink frame 604 c, thesidelink UE transmits SCI 664 in the sidelink resource 606 located inthe frequency subband 602 _(S1) to reserve a sidelink resource 606 in anext sidelink frame 604 d located at the frequency subband 602 _(S0).During the sidelink frame 604 d, the sidelink UE transmits SCI 668 inthe sidelink resource 606 located in the frequency subband 602 _(S0).The SCI 668 may reserve a sidelink resource 606 in a later sidelinkframe 604.

The SCI can also indicate scheduling information and/or a destinationidentifier (ID) identifying a target receiving sidelink UE for the nextsidelink resource 606. Thus, a sidelink UE may monitor SCI transmittedby other sidelink UEs. Upon detecting SCI in a sidelink resource 606,the sidelink UE may determine whether the sidelink UE is the targetreceiver based on the destination ID. If the sidelink UE is the targetreceiver, the sidelink UE may proceed to receive and decode the sidelinkdata indicated by the SCI. In some aspects, multiple sidelink UEs maysimultaneously communicate sidelink data in a sidelink frame 604 indifferent frequency subband (e.g., via frequency division multiplexing(FDM)). For instance, in the sidelink frame 604 b, one pair of sidelinkUEs may communicate sidelink data using a sidelink resource 606 in thefrequency subband 602 _(s2) while another pair of sidelink UEs maycommunicate sidelink data using a sidelink resource 606 in the frequencysubband 602 _(S1).

In some aspects, the scheme 600 is used for synchronous sidelinkcommunications. That is, the sidelink UEs may be synchronized in timeand are aligned in terms of symbol boundary, sidelink resource boundary(e.g., the starting time of sidelink frames 604). The sidelink UEs mayperform synchronization in a variety of forms, for example, based onsidelink synchronization signal blocks (SSBs) received from a sidelinkUE and/or NR-U SSBs received from a BS (e.g., the BSs 102 and/or 310)while in-coverage of the BS. In some aspects, the sidelink UE may bepreconfigured with the resource pool 608 in the frequency band 601, forexample, while in coverage of a serving BS. The resource pool 608 mayinclude a plurality of sidelink resources 606. The BS can configure thesidelink UE with a resource pool configuration indicating resources inthe frequency band 601 and/or the subbands 602 and/or timing informationassociated with the sidelink frames 604. In some aspects, the scheme 600includes mode-2 RRA (e.g., supporting autonomous radio resourceallocation (RRA) that can be used for out-of-coverage sidelink UEs orpartial-coverage sidelink UEs).

Cellular vehicle-to-everything (V2X) technology has applications forimproving commuter safety. However, conventional cellular V2X technologydoes not adequately address safety issues relating to pedestrians.Nowadays, almost every person on the street has a mobile device, such asa mobile handset or cellular enabled wearable. Under that assumption,density of V2X coverage may be increased to improve safety.

Unfortunately, always running a V2X stack, such as a pedestrian mode, onmobile devices unjustifiably increases battery consumption of thosedevices. That is, running the V2X stack (e.g., enabling a pedestrianmode) operates more baseband and radio frequency (RF) components. Itwould be desirable to reduce the envelope of regular cellular operationwhen the user is likely not near vehicles. On the other hand, it wouldbe highly inconvenient and unrealistic to expect mobile users tomanually turn on and off the V2X stack on their devices according totheir environment or other relevant circumstances. Furthermore, mobiledevices always transmitting V2X signals may unnecessarily strain the V2Xspectrum. Power consumption may be reduced by allowing a device tooperate in transmit-only mode, without receiving any communications.

According to aspects of the present disclosure, a framework fordynamically enabling or disabling a pedestrian mode detects when and forhow long it would be beneficial to enable the pedestrian mode. Thesolution determines when it would be beneficial to enable the pedestrianmode, by detecting when the mobile user begins walking or running. Themotion detection may occur with assistance from a motion co-processor, alocation engine, and/or similar information verified by a pairedBluetooth wearable. Alternatively, the solution may detect a mobile userswitching from an indoor location to outdoor location, for example, bysensing a background noise level. The information may be reconfirmedwith an online look-up of the device's location on a map. For example,the look-up may indicate that the device is near a road, indicating thedevice is outside. The background noise may indicate the device movedfrom a calm environment, to a busy environment, and then to an activeenvironment. Other indications that the pedestrian mode should beenabled include the device having no wireless local area network (WLAN)connection or the device being within coverage of a number of globalnavigation satellite system (GNSS) devices (e.g., global positioningsystem (GPS) satellites). The pedestrian mode may also be enabled, forexample, when the device is detected to be outdoors, but not in a car,which may have its own dedicated V2X stack.

In other aspects of the present disclosure, an audio system of a userequipment (UE) operating in an always-ON state may detect an emergency.The emergency may be detected by sounds that identify distress, such asa car crash or explosion. In these aspects, the mobile user may chooseto contribute to a road safety mesh system that may rely on servicelayer information to propagate via multiple “hops” over V2X users. Inother words, the user may choose to participate in an ad-hoc meshnetwork.

Some aspects of the present disclosure determine when to disable thepedestrian mode. For example, the pedestrian mode may be disabled whendetermining a re-evaluation timer expired and no enable criteria is met.The pedestrian mode may be disabled when the device is determined to beindoors or far from vehicles. The pedestrian mode may be disabled whenit is determined that the user is driving in a car that is alreadyequipped with dedicated V2X system.

Dynamic V2X enabling/disabling may be achieved through interworking ofsystems on the device. Such systems may include a motion co-processor, aGNSS receiver, a paired wearable, a WLAN radio system, and/or analways-on audio processor.

FIG. 7 is a flow diagram illustrating a decision process 700 fordetermining whether to enable a pedestrian mode, in accordance withvarious aspects of the present disclosure. The process 700 forevaluating whether to enable the pedestrian mode starts at block 702.After block 702, the process 700 determines whether a device is outsideor near any vehicles at block 704. If it is determined that the deviceis not outside or near any vehicles, the process 700 returns to block702. If it is determined that the device is outside or near a vehicle,the process 700 inputs this information to a decision engine 706. Fromblock 702, the process 700 also continues to block 708, where detectingof whether the user is running or walking occurs. The decision engine706 receives the information as to whether walking or running isdetected. For example, a Bluetooth connected wearable may provide thistype of information to the decision engine 706. The decision engine 706also receives information as to whether any cellularvehicle-to-everything (CV2X) traffic is present at block 710. Forexample, the device may detect other vehicles are present by detectingCV2X traffic from these vehicles.

If the output from the decision engine 706 indicates the pedestrian modeshould be enabled, OR a roadside emergency is detected at block 712, theprocess 700 then determines whether the user is driving at block 714. Ifit is determined that the user is not driving AND either the output fromthe decision engine 706 indicates the pedestrian mode should be enabled,OR a roadside emergency is detected, the pedestrian mode is enabled atblock 716.

At block 718, the process 700 determines whether to restart theevaluation. That is, a reevaluation timer is set based on the pedestrianmode decision at block 716. In some aspects, three types of timer valuesare possible. More details about the reevaluation timer will bedescribed with respect to FIGS. 9 and 10 . Once the reevaluation timerexpires, the process 700 returns to block 702. In some aspects of thepresent disclosure, a machine learning (ML) module 720 determines theamount of time for the reevaluation timer, instead of selecting one ofthe three timer values. That is, a more specific timer value may be setbased on an environment of the device and other relevant circumstances.

FIG. 8 is a flow diagram illustrating a decision process for determiningwhether a device is outdoors and near vehicular traffic, in accordancewith various aspects of the present disclosure. FIG. 8 shows additionaldetails of block 704 of FIG. 7 . A controller in a device 800 (e.g., aUE) detects whether vehicular traffic is present at time 802. Forexample, the device 800 may include an always-ON audio processor thatcan detect a vehicular traffic pattern. If vehicular traffic isdetected, at time 804, the controller determines whether WLANconnectivity is lost. The determinations at times 802 and 804 are ‘free’in the sense that there is no power penalty associated with thesedeterminations.

If both of the free determinations indicate that the device 800 may beoutside and near vehicles, at time 806, the controller may initiate aGNSS search to locate satellites. If a threshold number of satellites islocated (four satellites in this example), the device 800 may initiatefurther activity to determine whether it is outside and near vehicles.At time 808, the controller may perform a data call to an outsideservice. For example, the device 800 may perform a look-up of a map toassess whether the device 800 is near vehicles. For example, a cloudservice such as ‘How Loud’ may indicate how far the device 800 is fromtraffic considering typical environmental noise for that location basedon vehicular traffic. The determinations at times 806 and 808 are not‘free’ in the sense that there is a power penalty associated with thesedeterminations.

At block 810, the controller of the device 800 determines whether threeor more of the tests at times 802-808 are positive. If three or more ofthe tests are positive, at block 814, the device 800 determines it isoutside and near vehicular traffic. If fewer than three of the tests arepositive, at block 816, the device 800 determines, it is inside or awayfrom vehicular traffic. Of course, the threshold may be set at valuesother than three.

False positives output from the decision at block 810 may impactpossible power savings. Thus, a machine learning model 812 may improveperformance over time. The machine learning model 812 may account forambient noise decibels, a number of minutes the WLAN is out of service,the number of satellites detected, and the results of the data call. Themachine learning model 812 learns based on these parameters andadaptively makes the controller more or less aggressive.

FIG. 9 is a flow diagram illustrating a decision process 900 for settinga reevaluation timer, in accordance with various aspects of the presentdisclosure. The reevaluation time is discussed with respect to block 718of FIG. 7 . At block 902, it is determined whether the UE is in motion(e.g., the pedestrian carrying the UE is running or walking). Sensorsmay assist with this process. If it is determined that the UE is inmotion, at block 904 it is determined whether the UE is outdoors. Theoutdoor detection may be in accordance with the process described withrespect to FIG. 8 , for example.

If the UE is detected to be outdoors, at block 906, a reevaluation timeris enabled with a long duration. In some implementations, the longduration is ten minutes. Thus, at block 718 of FIG. 7 , the controllerwaits ten minutes before restarting evaluation at block 702. Returningto FIG. 9 , if the UE is not determined to be outdoors, the processcontinues to block 908, where it is determined if a number satellitesdetected is greater than a threshold amount (e.g., four satellites inthe example of FIG. 9 ). The determination at block 908 develops moreconfidence in whether the UE is outdoors, to prevent wasting power byreevaluating too frequently. If more than the threshold number ofsatellites are detected, at block 910, the reevaluation timer is set toa medium value, for example seven minutes.

If fewer than the threshold number of satellites are detected at block908, at block 912, it is determined whether cellular V2X communicationshave been received in the past Z minutes. The parameter Z may have avalue of, for example, five or ten minutes. It may be determined howlong since hearing from another vehicle while in the pedestrian mode. Ifit has been less than Z minutes, a short duration is set for thereevaluation timer at block 914. For example, the short duration may befive minutes in some implementations. If at block 912 it is determinedthat the time exceeds Z minutes, at block 916, it is determined whetherambient road noise exceeds a threshold. For example, it may bedetermined whether a peak to average ratio of the ambient noise is high,possibly indicating the presence of vehicular traffic. Such a conditionmay occur if the UE is near a road with cars passing quickly, while aGPS signal is blocked, for example, by trees. If the ambient noise has ahigh peak to average ratio, at block 918, the reevaluation timer is setto a long duration. If it is determined that the ambient noise does nothave a high peak to average ratio, the reevaluation timer is set to ashort duration at block 914.

At block 902, if it is determined that the UE is not in motion, at block920, it is determined whether the UE is outdoors. If the UE is outdoors,at block 922 it is determined whether CV2X communications have beenreceived in the past Z minutes. If it has been less than Z minutes, atblock 924, the reevaluation timer is set to a medium duration. If atblock 922 it has been determined that the time exceeds Z minutes, atblock 926, it is determined whether ambient noise has a high peak toaverage ratio. If it is determined that the ambient noise has a highpeak to average ratio, at block 928, the reevaluation timer is set to along duration. Otherwise, the revaluation timer is set to a shortduration, at block 930.

If the UE is not determined to be outdoors at block 920, at block 932,it is determined whether the UE has received CV2X communications in thepast Z minutes. If it has been less than Z minutes, at block 934, therevaluation timer is set to a short duration. Otherwise, at block 936,the reevaluation timer is disabled. For example, the process may waituntil the next trigger of running or walking (e.g., at block 708 of FIG.7 ).

According to aspects of the present disclosure, when an audio subsystemof the UE or the V2X receiver infers no congestion or no presence ofmultiple car entities in the neighborhood, scanning may be reduced to asubset of the resource blocks (RBs) at each time. In other aspects, thescanning may be reduced to a subset of the subframes every 100 ms. Thistechnique is helpful because devices keep the same transmission periodicresources for about 50 transmissions (e.g., about five seconds inuncongested states). In some aspects of the present disclosure, when thedevice is visible, the role of activating or deactivating the pedestrianmode may be delegated to road side units (RSUs).

Techniques of the present disclosure improve a trade-off among havingvery dense V2X coverage for commuter safety, stationary mobile devicesunjustifiably draining battery power without much benefit, andunder-utilizing the unique interplay of complex systems that mobiledevices commonly support.

In some cases, a pedestrian mode may be enabled more frequently thannecessary. For example, a user may move from indoors to a large openspace that has traffic noise from distant freeway. This scenario maycause unnecessary battery drain.

According to aspects of the present disclosure, benefits to a maximumpossible number of mobile devices and vehicles with V2X transceivers maybe provided. The techniques of the present disclosure may leveragedevices that have cellular V2X (CV2X) support in addition to regularcellular technologies.

As on-device capabilities related to application processors and/orsensors evolve, additional information from cameras, display brightnesssensors, etc., may be obtained to detect changes in the userenvironment. Such advancements may enhance a modem context awareframework and dynamically determine when to enable or disable vehicle topedestrian capabilities. Machine learning models may also improvethresholds and time values.

FIG. 10 is a flow diagram illustrating an example process 1000performed, for example, by a device, in accordance with various aspectsof the present disclosure. The example process 1000 is an example ofdynamically enabling and disabling a vehicle-to-everything (V2X)pedestrian mode for mobile devices. The operations of the process 1000may be implemented by a device, for example a UE 104.

At block 1002, the device detects whether it is in an outdoorenvironment in response to a start of a reevaluation timer. For example,the UE (e.g., using the antenna 352, receiver/transmitter 354, receiveprocessor 356, transmit processor 368, memory 360 and/orcontroller/processor 359) may detect whether the device is in an outdoorenvironment. The device may detect whether it is in an outdoorenvironment by sensing a background noise level or with an onlinelook-up of the device's location on a map. For example, the look-up mayindicate that the device is near a road, indicating the device isoutside. The background noise may indicate the device moved from a calmenvironment, to a busy environment, and then to an active environment.Other indications that the pedestrian mode should be enabled include thedevice having no wireless local area network (WLAN) connection or thedevice being within coverage of a number of global navigation satellitesystem (GNSS) devices (e.g., global positioning system (GPS)satellites).

A block 1004, the user equipment (UE) determines a mobility level of thedevice in response to the start of the reevaluation timer. For example,the UE (e.g., using the controller/processor 359, and/or memory 360) maydetermine the mobility level. Sensors, such as GPS sensors oraccelerometers, may assist with this process.

At block 1006, the user equipment (UE) enables a vehicle-to-everything(V2X) pedestrian mode in response to the device being in the outdoorenvironment and/or the mobility level exceeding a threshold value. Forexample, the UE (e.g., using the controller/processor 359, and/or memory360) may enable the V2X pedestrian mode. For example as noted withrespect to FIG. 7 , if it is determined that the user is not driving ANDeither the output from the decision engine 706 indicates the pedestrianmode should be enabled, OR a roadside emergency is detected, thepedestrian mode is enabled at block 716.

Implementation examples are described in the following numbered clauses.

-   -   1. A method of wireless communication by a device, comprising:        -   detecting whether the device is in an outdoor environment in            response to a start of a reevaluation timer;        -   determining a mobility level of the device in response to            the start of the reevaluation timer; and        -   enabling a vehicle-to-everything (V2X) pedestrian mode in            response to the device being in the outdoor environment            and/or the mobility level exceeding a threshold value.    -   2. The method of clause 1, further comprising enabling the V2X        pedestrian mode in response to detecting an emergency condition.    -   3. The method of clause 1 or 2, further comprising adjusting a        duration of the reevaluation timer based on whether the device        is in the outdoor environment and/or whether the mobility level        exceeds the threshold value.    -   4. The method of any of the preceding clauses, further        comprising adjusting the duration of the reevaluation timer        based on a length of time since receiving a V2X message.    -   5. The method of any of the preceding clauses, further        comprising adjusting the duration of the reevaluation timer        based on a level of ambient noise sensed by the device.    -   6. The method of any of the preceding clauses, further        comprising scanning for V2X messages on a subset of allocated        time and/or frequency resources, the subset determined based on        a length of time since receiving a V2X message.    -   7. The method of any of the preceding clauses, further        comprising scanning for V2X messages on a subset of allocated        time and/or frequency resources, the subset determined based on        a level of ambient noise sensed by the device.    -   8. The method of any of the preceding clauses, in which the        device comprises a user equipment (UE).    -   9. The method of any of the preceding clauses, further        comprising disabling the vehicle-to-everything (V2X) pedestrian        mode in response to the device not being in the outdoor        environment when the reevaluation timer expires.    -   10. The method of any of the preceding clauses, further        comprising disabling the vehicle-to-everything (V2X) pedestrian        mode in response to the mobility level being less than the        threshold value when the reevaluation timer expires.    -   11. An apparatus for wireless communication by a device,        comprising:        -   a memory; and        -   at least one processor coupled to the memory, the at least            one processor configured:            -   to detect whether the device is in an outdoor                environment in response to a start of a reevaluation                timer;            -   to determine a mobility level of the device in response                to the start of the reevaluation timer; and            -   to enable a vehicle-to-everything (V2X) pedestrian mode                in response to the device being in the outdoor                environment and/or the mobility level exceeding a                threshold value.    -   12. The apparatus of clause 11, in which the at least one        processor is further configured to enable the V2X pedestrian        mode in response to detecting an emergency condition.    -   13. The apparatus of clause 11 or 12, in which the at least one        processor is further configured to adjust a duration of the        reevaluation timer based on whether the device is in the outdoor        environment and/or whether the mobility level exceeds the        threshold value.    -   14. The apparatus of any of the clauses 11-13, in which the at        least one processor is further configured to adjust the duration        of the reevaluation timer based on a length of time since        receiving a V2X message.    -   15. The apparatus of any of the clauses 11-14, in which the at        least one processor is further configured to adjust the duration        of the reevaluation timer based on a level of ambient noise        sensed by the device.    -   16. The apparatus of any of the clauses 11-15, in which the at        least one processor is further configured to scan for V2X        messages on a subset of allocated time and/or frequency        resources, the subset determined based on a length of time since        receiving a V2X message.    -   17. The apparatus of any of the clauses 11-16, in which the at        least one processor is further configured to scan for V2X        messages on a subset of allocated time and/or frequency        resources, the subset determined based on a level of ambient        noise sensed by the device.    -   18. The apparatus of any of the clauses 11-17, in which the        device comprises a user equipment (UE).    -   19. The apparatus of any of the clauses 11-18, in which the at        least one processor is further configured to disable the        vehicle-to-everything (V2X) pedestrian mode in response to the        device not being in the outdoor environment when the        reevaluation timer expires.    -   20. The apparatus of any of the clauses 11-19, in which the at        least one processor is further configured to disable the        vehicle-to-everything (V2X) pedestrian mode in response to the        mobility level being less than the threshold value when the        reevaluation timer expires.    -   21. An apparatus for wireless communication by a device,        comprising:        -   means for detecting whether the device is in an outdoor            environment in response to a start of a reevaluation timer;        -   means for determining a mobility level of the device in            response to the start of the reevaluation timer; and        -   means for enabling a vehicle-to-everything (V2X) pedestrian            mode in response to the device being in the outdoor            environment and/or the mobility level exceeding a threshold            value.    -   22. The apparatus of clause 21, further comprising means for        enabling the V2X pedestrian mode in response to detecting an        emergency condition.    -   23. The apparatus of clause 21 or 22, further comprising means        for adjusting a duration of the reevaluation timer based on        whether the device is in the outdoor environment and/or whether        the mobility level exceeds the threshold value.    -   24. The apparatus of any of the clauses 21-23, further        comprising means for adjusting the duration of the reevaluation        timer based on a length of time since receiving a V2X message.    -   25. The apparatus of any of the clauses 21-24, further        comprising means for adjusting the duration of the reevaluation        timer based on a level of ambient noise sensed by the device.    -   26. The apparatus of any of the clauses 21-25, further        comprising means for scanning for V2X messages on a subset of        allocated time and/or frequency resources, the subset determined        based on a length of time since receiving a V2X message.    -   27. The apparatus of any of the clauses 21-26, further        comprising means for scanning for V2X messages on a subset of        allocated time and/or frequency resources, the subset determined        based on a level of ambient noise sensed by the device.    -   28. The apparatus of any of the clauses 21-27, in which the        device comprises a user equipment (UE).    -   29. The apparatus of any of the clauses 21-28, further        comprising means for disabling the vehicle-to-everything (V2X)        pedestrian mode in response to the device not being in the        outdoor environment when the reevaluation timer expires.    -   30. The apparatus of any of the clauses 21-29, further        comprising means for disabling the vehicle-to-everything (V2X)        pedestrian mode in response to the mobility level being less        than the threshold value when the reevaluation timer expires.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the aspects to the preciseform disclosed. Modifications and variations may be made in light of theabove disclosure or may be acquired from practice of the aspects.

As used, the term “component” is intended to be broadly construed ashardware, firmware, and/or a combination of hardware and software. Asused, a processor is implemented in hardware, firmware, and/or acombination of hardware and software.

Some aspects are described in connection with thresholds. As used,satisfying a threshold may, depending on the context, refer to a valuebeing greater than the threshold, greater than or equal to thethreshold, less than the threshold, less than or equal to the threshold,equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described may beimplemented in different forms of hardware, firmware, and/or acombination of hardware and software. The actual specialized controlhardware or software code used to implement these systems and/or methodsis not limiting of the aspects. Thus, the operation and behavior of thesystems and/or methods were described without reference to specificsoftware code—it being understood that software and hardware can bedesigned to implement the systems and/or methods based, at least inpart, on the description.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various aspects. In fact, many ofthese features may be combined in ways not specifically recited in theclaims and/or disclosed in the specification. Although each dependentclaim listed below may directly depend on only one claim, the disclosureof various aspects includes each dependent claim in combination withevery other claim in the claim set. A phrase referring to “at least oneof” a list of items refers to any combination of those items, includingsingle members. As an example, “at least one of: a, b, or c” is intendedto cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combinationwith multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c,a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering ofa, b, and c).

No element, act, or instruction used should be construed as critical oressential unless explicitly described as such. Also, as used, thearticles “a” and “an” are intended to include one or more items, and maybe used interchangeably with “one or more.” Furthermore, as used, theterms “set” and “group” are intended to include one or more items (e.g.,related items, unrelated items, a combination of related and unrelateditems, and/or the like), and may be used interchangeably with “one ormore.” Where only one item is intended, the phrase “only one” or similarlanguage is used. Also, as used, the terms “has,” “have,” “having,”and/or the like are intended to be open-ended terms. Further, the phrase“based on” is intended to mean “based, at least in part, on” unlessexplicitly stated otherwise.

What is claimed is:
 1. A method of wireless communication by a device,comprising: detecting whether the device is in an outdoor environment inresponse to a start of a reevaluation timer; determining a mobilitylevel of the device in response to the start of the reevaluation timer;and enabling a vehicle-to-everything (V2X) pedestrian mode in responseto the device being in the outdoor environment and/or the mobility levelexceeding a threshold value.
 2. The method of claim 1, furthercomprising enabling the V2X pedestrian mode in response to detecting anemergency condition.
 3. The method of claim 1, further comprisingadjusting a duration of the reevaluation timer based on whether thedevice is in the outdoor environment and/or whether the mobility levelexceeds the threshold value.
 4. The method of claim 3, furthercomprising adjusting the duration of the reevaluation timer based on alength of time since receiving a V2X message.
 5. The method of claim 3,further comprising adjusting the duration of the reevaluation timerbased on a level of ambient noise sensed by the device.
 6. The method ofclaim 1, further comprising scanning for V2X messages on a subset ofallocated time and/or frequency resources, the subset determined basedon a length of time since receiving a V2X message.
 7. The method ofclaim 1, further comprising scanning for V2X messages on a subset ofallocated time and/or frequency resources, the subset determined basedon a level of ambient noise sensed by the device.
 8. The method of claim1, in which the device comprises a user equipment (UE).
 9. The method ofclaim 1, further comprising disabling the vehicle-to-everything (V2X)pedestrian mode in response to the device not being in the outdoorenvironment when the reevaluation timer expires.
 10. The method of claim1, further comprising disabling the vehicle-to-everything (V2X)pedestrian mode in response to the mobility level being less than thethreshold value when the reevaluation timer expires.
 11. An apparatusfor wireless communication by a device, comprising: a memory; and atleast one processor coupled to the memory, the at least one processorconfigured: to detect whether the device is in an outdoor environment inresponse to a start of a reevaluation timer; to determine a mobilitylevel of the device in response to the start of the reevaluation timer;and to enable a vehicle-to-everything (V2X) pedestrian mode in responseto the device being in the outdoor environment and/or the mobility levelexceeding a threshold value.
 12. The apparatus of claim 11, in which theat least one processor is further configured to enable the V2Xpedestrian mode in response to detecting an emergency condition.
 13. Theapparatus of claim 11, in which the at least one processor is furtherconfigured to adjust a duration of the reevaluation timer based onwhether the device is in the outdoor environment and/or whether themobility level exceeds the threshold value.
 14. The apparatus of claim13, in which the at least one processor is further configured to adjustthe duration of the reevaluation timer based on a length of time sincereceiving a V2X message.
 15. The apparatus of claim 13, in which the atleast one processor is further configured to adjust the duration of thereevaluation timer based on a level of ambient noise sensed by thedevice.
 16. The apparatus of claim 11, in which the at least oneprocessor is further configured to scan for V2X messages on a subset ofallocated time and/or frequency resources, the subset determined basedon a length of time since receiving a V2X message.
 17. The apparatus ofclaim 11, in which the at least one processor is further configured toscan for V2X messages on a subset of allocated time and/or frequencyresources, the subset determined based on a level of ambient noisesensed by the device.
 18. The apparatus of claim 11, in which the devicecomprises a user equipment (UE).
 19. The apparatus of claim 11, in whichthe at least one processor is further configured to disable thevehicle-to-everything (V2X) pedestrian mode in response to the devicenot being in the outdoor environment when the reevaluation timerexpires.
 20. The apparatus of claim 11, in which the at least oneprocessor is further configured to disable the vehicle-to-everything(V2X) pedestrian mode in response to the mobility level being less thanthe threshold value when the reevaluation timer expires.
 21. Anapparatus for wireless communication by a device, comprising: means fordetecting whether the device is in an outdoor environment in response toa start of a reevaluation timer; means for determining a mobility levelof the device in response to the start of the reevaluation timer; andmeans for enabling a vehicle-to-everything (V2X) pedestrian mode inresponse to the device being in the outdoor environment and/or themobility level exceeding a threshold value.
 22. The apparatus of claim21, further comprising means for enabling the V2X pedestrian mode inresponse to detecting an emergency condition.
 23. The apparatus of claim21, further comprising means for adjusting a duration of thereevaluation timer based on whether the device is in the outdoorenvironment and/or whether the mobility level exceeds the thresholdvalue.
 24. The apparatus of claim 23, further comprising means foradjusting the duration of the reevaluation timer based on a length oftime since receiving a V2X message.
 25. The apparatus of claim 23,further comprising means for adjusting the duration of the reevaluationtimer based on a level of ambient noise sensed by the device.
 26. Theapparatus of claim 21, further comprising means for scanning for V2Xmessages on a subset of allocated time and/or frequency resources, thesubset determined based on a length of time since receiving a V2Xmessage.
 27. The apparatus of claim 21, further comprising means forscanning for V2X messages on a subset of allocated time and/or frequencyresources, the subset determined based on a level of ambient noisesensed by the device.
 28. The apparatus of claim 21, in which the devicecomprises a user equipment (UE).
 29. The apparatus of claim 21, furthercomprising means for disabling the vehicle-to-everything (V2X)pedestrian mode in response to the device not being in the outdoorenvironment when the reevaluation timer expires.
 30. The apparatus ofclaim 21, further comprising means for disabling thevehicle-to-everything (V2X) pedestrian mode in response to the mobilitylevel being less than the threshold value when reevaluation timerexpires.